Electrotherapeutic apparatus.



0. E. CAMPBELL. l ELEGTROTHEHAPEUTIG APPARATUS.

APPLIOATON FILED NOV. 10, 1909.

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W :TL-Ya e es es C. E. CAMPBELL. BLECTROTHBRAPBUTIG APPARATUS.

APPLICATION FILED NOV. l0, 1909. QQ@ Patented Deo. 19, 1911.

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I G. 1:..GAMPBELL BLEGTROTHERAPBUTIG APPARATUS.

. APPLIUATION FILED NOV. 10, 1909.

1,012,326. Patented Dec. 19,1911.

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onARsom/AL o 55 C. E. CAMPBELL.

BLEGTROIHERAPBUTIG APPARATUS.

APPLIUATION FILED NOV.1o, 1909.

1,01 2,326, Patented Dec. 19, 1911*.

6 SHEETS-SHEET 4,

Wim-:asses: mvwGT-n C. E. GAMPBBLL. ELECTROTHEBAPEU'IIG APPARATUS. APPLICATION FILED NOV. 10, 1909.

(1,012,326. Patented Dec.19,1911.

6 SHEETB-SHBBT 5.

C. E. CAMPBELL. ELECTBOTHERAPEUTIG APPARATUS.

APPLICATION FILED 11011.10, 19o9.

1,012,326. Patented De@.19,1911.

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UNITED sTATns PATENT orricn. I

CHARLES CAMPBELL, OF LYNN, MASSACHUSETTS, ASSIGNOR T CAMPBELL ELECTRIC l COMPANY, 0F LYNN, MASSACHUSETTS, A CORPORATION OF MASSACHUSETTS.

ELECTROTHERAPEUTIC APPARATUS.

A Application led November 10, 1909. Serial No. 527,153.

To all whom 'it may concern.'

Be it known that I, CHARLES E. CAMP- BELL, a citizen of the United States, residing at Lynn, in the county of Essex and State of Massachusetts, have invented certain new and useful Improvements in Electrotherapeutic Apparatus; and I do hereby declare the following to be a full, clear,I and exact description of the invention, such as will enable others skilled in the art to which it appertains to lmake and use the same.

My inventlon relates to' electro-therapeutic apparatus adapted for use in connection with the various lapplications of electricity to medicine and surgery, such as radiography, cautery, diagnosis, and thel ap-4 plication of electric currents to the body.

One object of the invention is to produce a simple'` and compact apparatus for the purposes above set forth, in which the several currents of the different characters and tensions required for the purposes referred to may be derived in a simple and safe manner from a. single source of supply.

To this end my invention comprises 'a transformer adapted to produce currents of different tensions in a plurality of independent circuits either at the same time or separately.

Another object of the invention is to produce an apparatus of the kind referred to which shall be insured both against injury to itself arising from internal causes, and

against injury to tlie`operator arising either from careless operation or from accidental derangement in the apparatus.

To this end the invention comprises various novel arrangements and constructions which, together with novel and useful features of` operation and construction not hereinbefore specifically referred to, will be set forth in connection with the following i description of the illustrated embodiment of the invention.

In the accompanyingdrawings, Figure l is a diagram of thel electric circuits 1n an apparatus constructed in accordance with the present invention; Fig. 2 is a front elevation Yof the apparatus diagrammatically"l illustrated in Fig. `1;.Fig. 3 is a plan View of the apparatus; Fig. 4 is a plan view of the apparatus with the'controlling handles, the cover-plate and other external parts removed; 5 is a plan view of the appas magnetic circuit.

ratus with the connection-board as well as the external parts removed; Fig. 6 is a vertical section taken on line m-in Fig. 4, looking from front to rear, of the removable connection-board and parts carried thereby; Fig. 7 is a vertical section on line '1f-g] in Fig 5, looking from the rear, of the primary regulator; Fig. 8 is a detailed plan view of the spark gap of the high-tension transf ormer; and Fig. 9 is a vertical section on line a-a in Fig. 8, looking from front to rear.

The illustrated embodiment of my invention maybe best understood by consid'- ering first the diagram of the electric circuits, Fig. l of the drawings. The apparatus comprises, as is common in' apparatus of this type, a high-tension transformer adapted to be energized by alternating electricy currents such as may be obtained-from ordinary electric lighting. systems. .This transformer generates 1n its principal secondary winding an alternating current of high tension, which is converted into a succession of oscillatory discharges by vmeans of a condenser and a spark gap. In combination with the high-tension transformer I use a high-frequency induction coil of the type known as the Tesla coil, this coil operating to generate alternating currents of high frequency and of such high tension as to evince many of the characteristics of static electricity.

In the diagram the high-tension transformer is designated generally by the refence number 1 and the Tesla coil by the reference number 2. rlhe transformer 1, for reasons which will be stated hereinafter, is of what is commonly known as the core type having a core comprising two parallel legs 3 and 4 connected at their ends by end pieces so as to constitute a closed The primary windings of the transformer are placed upon the leg 4 and constitute a number of separately- Y wound coils. At the ends of the leg 4 are main primary coils 5 and 6 which are alwaysoperat-ive whenthe transformer is in use. The coils 5 are "connected with vone of theterminals 7 through which thetransformerv is supplied with the alternating current by which it is energized. After" traversing the coils 5 the current passes, through a wire 8, to the coils 6 which are wound in the same sense as'the coils`5. From the coils 6 the current passes through a wire 9 to a series of primary coils 10 arranged between vthe coils and 6. Each of the coils 10 has an independent connection with one of the contactfypoints of the primary regulator 11,

and the movable contact member of the primary regulator is connected, by a wire 12, with the other supply terminal 13.

The above-described arrangementof primary coils constitutes means for varying the amount of current passing through the primary windings and energizing the transformer. When fewer turns are used in the primary winding the ratio of transformation between the secondary and primary voltages will be increased, the secondary Winding being more strongly energized and forcing more current through the different external circuits connected thereto, and the primary will in consequence admit a' greater primary current from t-he supply mains. When less energy is desired, more turns are used in the primary winding and the ratio between the secondary and the primary voltages is diminished, the result being that the secondaryvvoltage is lessened, and less current forced through the various secondary circuits, with consequent diminution of the amount of current drawn by the primary from the'supply mains. The impedance of any turn of the primary winding will be due toits own ohmic resistance and to the magnetic flux which links said turn. The magnetic lines which linkf'fboth the primary and secondary and'constitute the effective flux made up, one component of the total iuX linking said turn ofi/the primary, and the impedance due to this', component of the flux will vary with thejimpedance of the secondary circuit. Another component of the total flux is the leakage flux, or the magnetic lines linking said turn which do not cut the secondary windings, and lthe impedance due to the leakage flux is not dependent upon the impedance of the secondary circuit. The effective flux does useful work in exciting the secondary','while the leakage flux acts only to Any primary turn is of greater efiiciency the larger the ratio is between the effective andthe leakage iuX linking the turn. This great-er efficiency of some turns of the primary over others will depend upon their position upon the magnetic core with respect to the secondary coil. I have accordingly placed the coils 5 and 6, which are always in'circuit,'

atY the ends of the primary leg 4 of the core, and in a position upon the magnetic circuit closest t0 the high potential secondary 14, giving the coils 5 and 6 the position of highest efficiency. The regulating coils 10, which are not always in use, are placed on the magnetic circuit at a greater distance from the secondary windings than the windings gap.

or less of the primary coils 10 theturns of the primary winding, and thus its impedance, may be increased or diminished so as to vary the amount of current flowing through the primary winding.

The main secondary winding 14 of the transformer is mounted upon the'leg 3 of the core and is connected, by wires 15 and 16, with the spark gap 17.

The primary winding consists of a com- I paratively few turns of wire, and the secondary winding of a. greater number of turns, so that the transformerfacts as a stepup transformer to step-up' the primary Voltage to a high tension secondary potential. By placing the primary and secondary windings upon diferent legs of the transformer core, they are more completely separated and better insulatedfrom each other to guard against any possible'break-down between the primary and secondary.-

A condenser 18 is connected with the wire 16 by a wire 22, at one terminal, and the other terminal of the condenser is connected by a. wire 19, with the primary winding 20 of the Tesla coil. The winding 20 is conneet-ed at its other. terminahby a wire 21, with the other side of the spark gap 17. By this arrangement the condenser is alternately charged and discharged through the winding 20 of the Tesla coil, and the discharges have the .oscillatory character due to the use of the condenser and the spark In order to vary the frequency of the oscillatory discharges so as to modify the character of the currents produced by the Tesla coil, the condenser is arranged to have a Variable capacity which is regulated by means of a frequency-regulator 23., This regulator comprises a conductive sector which may be rot-ated into position to connect together or disconnect a number of condenserplates of the same set as the uppermost plate, which plate is normally connected with the spark gap through the wire 22. In this way a: greater or less number of plates is rendered operative and the capacity of the condenser and, consequently, its rate of charge and discharge is thus regulated.

The terminals of'v the secondary winding 24 of the Tesla coil are' connected, by conspark gap 2T, which is adjustable, in the ordinary manner, by means of a sliding rod 2S. ln place ot connecting the primary and secoiulary windings of the Tesla coil with the earth in the usual manner, the lowermostplate 2S) of thc condenser 18 is connected. by a wire, 30, with the wire 1&2- connccted with the. primary winding ot the transformer and with the supply system by which the apparatus is energized. This arrangement. constitutes in general the equivalent. of a ground iliade in the 'ordinary manner. but it has advantages which will be hereinafter Apointed `out. Currents of the characters usually employed in therapeutics and derived from a high-frequency coil are derived from the Tesla coil 2 in the present invention, either `t'rom the terminals of the spark gap 2T or by other connections illustrated-in Fig. l. A current of the character usually designated as a. dArsonyal current is obtained through terminals connected, by wires 32, 232% and 2G. with a portion of the secondary winding 24. f This portion is made of heavier wire than' the rest of the secondary winding. and the arrangement is such that the d`.\rsonval current supplied in this manner is oi lower tension but greater volume than the. current generated in the Tesla secondary as va whole. t current. of high frequency but ot lower tension than that produced in the secondary winding 2l is obtained through terminals connectedby wiresl 84 and 35 with the terminals of the primary winding 2O of the Tesla coil. This current may be designated as a thermo-.faradic current.

ln addition to the high-tension and hight'requency currents above referred to, the amiaratus is arranged to supply alternatingr currents of comparatively low" tension and ot the frequency of the alternating current by which the apparatus is energized. @ne of these currents, which may be designated as ay sinusoidal current, and which is designed for direct personal application, is induced in an auxiliary secondary winding 36 in the transformer l. and this secondary winding, for reasons .which will be hereinafter pointed out. is located upon the same leg of the ,core as the primary winding voi" the transformer and is interposed between the coils of the primary winding. The sinusoidal currentis obtained from terminals connected, by wires` 37 and 38, With the terminals oit the winding 36.

ln addition to the current-s abovede'- scribed for direct application. the apparatus is designed to furnish currents for indirect use. such currents being adapted for the operation of cauterizing 4apparatus and diagnostic lamps. The current for the diagnostic Alamp is obtained from terminals which are connected, through wires 38, 39

and '10. and through a variable resistance device Ill. with the secondary winding 36. The connections are arranged as shown in Fig. l so that in the production of this current only a portion of the winding 36, is employed, so that the lamp current isof The variable resistance device 41 constitutes a regulator for the diagnostic lamp.,

The cautery current is obtained from another auxiliary secondary winding, 42, arranged adjacent to the winding 36. This winding l2 is so proportioned as to produce 4 a current of ver)7 low tension, which may be safely used for the purpose designated. 'The cautery current is obtained from terminals connected wit-h the winding 42 by means of wires v-13 and 44.

To furnish at all times an `indication when the transformer is in operation, a small electric lamp l5, designated as a pilot light, is connected across the wires 42 and 43 and-this lamp glows whenever there is Ianylow of current in the primary winding` of the transformer.

The mechanical construction of the apparatus may now be considered. This is most fully disclosed in Fig. 5 of the drawings, which shows a plan View of the interior arrangements of the apparatus. As shown in- Fig. the primary windings 5 and 6 each constitute two separately-Wound coils. Owing to this arrangen'ient and to the further diyision of the primary winding into the separately-wound coils 10. the entire primary winding of the transformer is divided into a large number of small sections. lt has previously been connnon to arrange thc secondary winding of an induction coil or high-tension transformer in separate sections in this manner. for the purpose of securing better insulation. but so far as T am aware the arrangement is novel in connection with the primary winding of a transformer or coil.- The utility ot' this arrangement results from the production in highfrequency'apparatus of static currents and waves of very high tension and of incidental character, which have a serious tendency to escapefrom the circuits of the apparatus and to leap considerable air spaces in prefpedance. primary winding of the transformer and 1t cial precaution there is danger of the disruptive discharge of such currents through down of the insulation therein, leading to 'the product-ion ot destructive arcs. T have mary in separate coils or sections as 'above winding is so improved as to protect it against. the elects which I have described.

erence to following conductors of high iin-' Such Waves or currents occur 1n has'beenl found that in the absence of spe'A found, however. that by winding-the prilower tension than the. sinusoidal current.--

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the primary and the consequent breaking described, the insulation of the primary in they primary circuit, tend to actas secondary coils with relation to the main coils 5 and 6, precisely after the manner of an auto-transformer, that is to say, a potential in the coils 10n is induced by the magnetic" flux in the core due to the action of the coils 5 and 6. This potential is 'opposite to that of the alteriiating current by which the primary windling is energized, and when the coils 10 are not connected in series with the main coils Ithe `difference `in potential between the left-hand coil l0 and the adjacent right-hand coil 5 is much higher than any difference in potential due to the energizing current alone. Toguard against evil effects from 4this circumstance, a plate 46 of insulating material is interposed between the coils 5 and the coils l0.

Thecontrol of the transformer by varying the amount of primary winding in operation is an economical method, since the flow of current is controlled not by waste of current in external heat-producing resistance devicessuch as are commonly used, but by the impedance in the primary winding itself. The control of thetransformer is thus accomplished in an economical and eective manner without the use of' any additional parts`except the controlling switch, and the bulk of theapparatus is thus minimized.

The construction of the spark gap 17 is illustrated particularly in Fig. 8. This spark gap is provided with an adjustable member 49 which has a flat face covered by athi'n plate of silver. The disruptive discharge be- .tween the 'spark-gap. members heats them and causes their surfaces to o xidize. I have found that a metal of which the oxid so produced ,is electrically-conductive o crates 1n aj much more uniform and satis actory manner than' a metal of which the oxid acts as an insulating medium, and for this purpose I have found that silver is well adapted,

. since its oxid has the required conductivity.

Themember 49 is adjustable toward and from the other member of the spark4 gap,

and to this'end'i's` mounted upon a screw 50j which is in threaded engagement with a metal sleeve 51. The outer end ofl the screw 50 is provided' with a'l head 52 by means of which it vmay ber 49 and vary the length of the sparkf To prevent over-heating ofthe spark-gapmember, the sleeve v51 is provided with'heatradiating flanges 53.-v The lsleeve 51 .is mounted. upon a plate 55 whichengages a slot passing through the -fianges 53, as shown j particularly in Fig. 9. This plate 55 is fixed ...upon a porcelain block.. 47 which 4forms 'a' base for the spark' 'gap. Thev plate 55 has a resilient tongue 56 which be turnedto adjust the mem-v j y normally springs 'upwardly above-the plane of the body ofthe .spark-gap screw 50 by means plate so as to engage the foremost flange 53 and therefore thev and prevent this flange,

member, from slidingl outwardly upon the plate 55. When itis desired, however, to remove the parts from theirnormal position, the tongue 56 may be pressed downward into line 4with the slot in the radiating liianges and the parts may then be withdrawn through an opening provided for this purpose in the front of the casing of the apparatus.

To shield the other parts of the apparatus from the heat and the fumes, produced by the discharge through the spark gap, vertlcal walls 48 of insulating material are fixed to the sides of the porcelain base 47, and as shown in Figs. 3 and 4, an opening 1s pro-1 vided through the top of the casing both to allow 'nspection of the spark gap and. to provi e for the escape of heated fumes.

The fixed member 60 of the s ark gap is similar in form to the adjusta le member 49 and is also provided with heat-radiating flanges. This member is mounted in a similar manner upon-a retaining tongue 63 similar to the retainlng tongue 56 above described.

To maintain a good electrical connection between the adjustin lscrew 50 and the sleeve 51, a screw-t readedring 57 is mounted upon the screw and is provided with two rearwardly-projecting pins 58 which loosely engage openings in the sleeve.l The spring-pressed member or ring 57 is prevented'from rotation with the adjusting of the said pins 58. Spiral springs surround the pins and force the threaded ring 57 constantly against the threads of the screw 50 with suicient pressure to maintain a ,close electrical contact and also to prevent accidental rotation of the adjustingscrew 50 dueto vibrations in the apparatus. The female screw threads of the spring-pressed ring 57 press forwardly against the malescrew threads of the screw fixed plate 62 having a.

50, while the female screw threads of the .threads of the screw 50 and the threads of the ring 57 and sleeve 51 whereby a close electrical contact is maintained and the screw 50 1s prevented from -turning too V easily.

A l e plates 54I and 62 are providedu with 'connction'members 59 by which they are connected with/the Wires fromv the secondary winding of the transformer 1.

` The construction of the primary regulator 11 is illustrated'parti'cularly in Fig. 7. This device is provided with a base 64 of insulating material, and for this purpose I have liso cated so as to afford a resilient engagement with the square socket `in the handle, operating .to maintain the handle frictionally in place while permitting it to be readily disengaged when necessary.

lThe stem 68 is journaled in a sleeve 6l and the sleeve is secured in place and connectedwith the conduct-or 12 by means of a nut 71 threaded upon the sleeve. A spiral spring 66 engages at one end the nut '71 and at its other end the collar 67 fixed on the stem 68. This spring operates 4to maintain constantly a good electrical connection between the stem and the nut 71 and conductor 12. end a metal. arm 70 bearing a contact button. The contact button may be moved, by rotating the stem 68, into engagement with either of a series of spring-pressed contact members 72 which are mounted in the base 64:, and in this way the conductor 12 may be connected alternatively, as indicated in Fig. 1, with the wires connected with the primary coils l0. The connections between the coils` 10 and the contact members 72 are .illustrated in Fig. 5. To retain the primary controller in its several positions, a plate of y insualting material 73 Yis mounted upon the stem 68 and is engaged by a spring-pressed ball 74 mounted on the base 64.v By means of suitable recesses in the upper surface of the'plate 73, the retainer may be caused` to arrest the motion of the regulator at points where the contact members are squarely in engagement with each other. The spring 66 permits the stem to yield vertically and V ,thereby facilitates the disengagement of the recesses from the retainer when the regulator is moved from contact to Contact.

It. is desirable p to prevent retrograde movement of the primary regulator by which it might be turned so as to throw vthe transformer into full operation at once,`

i and for this purpose a spring-pressed` member 103, similar in construction to the contact members 72, is mounted in such position that it vwill engage a shoulder 104, shown in dotted lines in Fig. 5, upon the plate 73. The position of the parts is such as to arrest the contact arm if it be attempted to turn it backward into engagement with-the last of the series of contact members 72 by which the direct connection is made between the conductor 12 and the wire 9.

Owing to the large number of circuits and connections necessary in an apparatus of the present character, it is diiicult and inconvenient to make the necessaryconnections through or upon the baseeboard or The stem 68 carries at'its lower the casing of the apparatus in the ordinary manner and I have, therefore, devised an arrangement by which the connections of the various portions of the apparatus are simplified, this arrangement being such also as to permit the removal of the cover of the ofthe connect-ions so that access may be readily and convenientlyhad'to the interior partsof the apparatus for purposes of examination and repair.

To the above ends I provide the casing Aapparatus,without the manipulation of any of the apparatus with a member upon which replacedin position, the conductors are thereby'engaged, and in this manner the terminals are connected with the interior parts of the apparatus without attention on the part of the operator.

`The connection member is embodied, in the illust-rated apparatus, in \a plate or board 81 of wood orother non-conducting material which normally covers the apparat-us, with the exception of the Tesla coil 2, and this board is normally secured in place by means of screws 93. The'board 81, which I shall hereinafter designate as the connection-member, carries, with one exception, the exterior terminals 83 through which the dArsonval, thermo-faradic and sinusoidal currents are derived and also the' terminals for the diagnostic lamp, and the cautery current. These various terminals arepconnect'ed, by means of wires and other conducto-rs shown principally by dotted lines in Fig. 4, with a` numberv of contact 'devices 105 fixed tothe bottom of the board.

The contact devices 105 are arranged in aA line in such position as to be directly above a cross bar 77 fixed in the casing'of the apparatus directly beneath the connection-l member. This'cross bar 77 is-made of wood or other non-conducting material and it carries contact'devices 8 in the'form of flat metal plates arranged in positionl to engage the Contact devices'105 when the connectionmember is in position.v To insurev a good contact bet-Ween the Contact devices 78 and 105, the former areprovided with threaded stems 80 which project upwardly through' the connection-member and are provided withnuts 92 by which the board is drawn firmly down into position.

When the nuts'92 and the screws` 93 are removed the connection-member may be freely removed from the casing thereby automatically disconnecting all of the external terminals from the apparatus, and when theconnection-memb'er is replaced the cirregulator.

cuits are automatically restored again by 4the operation of the contact devices-78 and 105.

In addition to the external terminals andtheir connections, the connection-member carries a socket 85 for the reception of one of the pillars 102 of the spark gap .of the Tesla coil. This socket 85 is provided w'ith an annular recess 86 forthe reception of the plate 89 of insulating ma-terial and carries a conductive cross-arm 90 which engages the several contacts v91 of the resistance coil by which the strength of current in the lamp is regulated. The socket 82 .for the pilot lamp 45 is also carried upon the connection-member.

The construction of the frequency-regulator 23 is similar in general to-that of the primary controller 11 except that the frequen'cy-regulator. is' provided with asector ofy conductingv material adapted to engage simultaneously any fnumber of the springpressed contacts 106, as indicated diagrammatically in Fig. 1. The frequency-controller is provided-with a knob or handle 98 similar to the knob 69 of the primary regulator. y The conductor 25, connecting the secondary winding of the Tesla coil with the spark gap 27, passes through a pillar 102 mounted in a socket 100 similar to the socket 85 already described.

The entire apparatus is covered by a plate 94 of rubber or other insulating material, and collars 95, threaded to ,the sockets 85- and 100 are screwed down upon the upper surface of this plate. The sockets are arranged to project well above-the apparatus to prevent discharges from the pillars-to the parts below the sockets. The terminals 83, etc., are covered by caps 96 of insulating material so that there are no exposed con-y ductors from which accidental ocks` may be obtained. The terminals 7 and 13 ofthe primary winding of the transformer are located in a socket 101, through which connection maybe made with a screw plug, 1n

the ordinary manner, to introduce the alternating current by which the 'apparatus is energized. .The arrangement of the vapl'iaratus throughout issuch as to prevent, so far as possible, accident either yto the operator or tg) theiapparatus itself'dueeither toi'nternal derangements in the apparatus or' to careless handling on the' part.ofv the operator.

v A further advantage resulting arrangement of themain primary coils 5 One means has already been described by which disruptive discharges in the primary winding of the transformer are prevented.

In this connection, however, the supplemental plate 29 of the condenser, hereinbefore described, serves as an additional safeguard, since, without constituting an actual metallic connection between the transformer and the high-tension portions of the apparatus, it operates in the manner ofa ground to ai'ord an outlet for the static waves or impulseswhich might otherwise ind a way through the primary winding.

litself a protection against the action of the high-tension oscillatory currents generated, sinceit ermits a sufficient separation of the primary `and secondary windings to prevent occurrence of disruptive discharges from the secondary winding through the primary Winding. This form of transformer has thus peculiar advantages when' used in connection, with a condenser and a spark gap to produce oscillatory currents 'of high tension, and such an arrangement is novel so far as I am informed. f s

from the and 6 at the extremities of the leg 4 of the transformer core resides in the fact that the principal portions o f the primary winding are thus brought as close as posslble to the secondary winding, so that the magnetic paths connecting the primary and secondary windings are thus of the shortest"possi ble length and thus efficiency and economy in'. the operation of the transformer are secured. This arrangement also permits the location `of the primary-regulating coils 10 at a point where'their inductive effect is slight, so that the impedance of these coils may. act more effectively to regulate the production of current in .the SeCOIldaYlls windings', currents of any volumes and ten- Asions withinthe extreme limitations of the apparatus may-be secured.

ferredembodiment .ofv the .invention I have found that for the 'production'. of thecau- In. the pre- It also prevents severe shocks to the operaiso tery current awi-nding of very few turns of heavy wire adapted to give a heavy current. under an E. M. F. of about three volts gives satisfactory results while restricting the voltage to such low tension as to render it perfectly safe and convenient for use in cauterizing apparatus. In the diagnostic lamp, I find an E. M. F. of ten volts to be sutiicient, while in the sinusoidal circuit I employ an E. M. F. of twenty-four volts .and the winding 36 is, therefore, suitably proportioned to 'produce such voltages.

The position of the secondary windings 3G and 42 upon vthe saine leg of the transformer as' the primary windings is a novel feature of importance, since it secures economy in space by placing these secondary windings at a. point where primary windings would have a comparatively low etticiency-in exciting the secondary winding 14. Moreover, by placing the secondary windings 36 and 42 upon the same leg and between the two primary coils, a good magnetic linkage is obtained between these windings and the primary, with a correspondingly good efficiency of current t'ansformation. The arrangement has a further advantage in thatit removes the comparatively low-tension secondary windings from the neighborhood of the high-tension secondary winding 1-1 and thereby reduces the liability of disruptive discharges in the transformer.

A detail of construction by which the reception of dangerous shocks by a patient or operator is avoided consistsiin the use of en tirely independent conductors, such as the wires 21 and 34, for connecting the thermofaradic tern'nnals and the spark gap 17 with the terminals of the Tesla coil primary 20,

as shown diagrammatically in Fig. 1. With the connection so arranged, if either of the connections shouldbecome accidentally broken the result would be merely to disconnect the thermo-faradic terminals entirely from the apparatus. If, on the otherghand, the wire were united tothe wire 21, or vice-versa, in place of the independent connections with the primary winding' 20, a danger-mis shock might result from accidental breakage of the common connection with the winding 20. In such an event the therino-faradic' terminals would constitute the only path for the discharge of the condenser, which discharge would pass through the person connected with these terminals, whereas in the normal operation of the vapparatus the primary winding 20, which consists of very few turns of a heavy conductor, and therefore has comparatively low impedance, is connected in .shunt with'the thermo-faradic. terminals so as to conduct the greater part of the discharge from the condenser. l

Another danger to be .guarded against in the operation of the apparatus resides in the possibility of connecting applicators to one of the dArsonval terminals and one of the thermo-faradic terminals, so as to put the patient or the operator into circuit withthe secondary windings of both the transformer and the Tesla coil. Such a result may occur,

for example, by using the right-hand dArsonval terminal and the upper thermofaradic terminal in Fig. 1. 'lo prevent danger from such a. cause, the windings of the Tesla .coil are so arranged and connected that in' a circuit formed asabove described they oppose each other` so that. the. resulting flow of current is equal to the difference and not to the sum of the currents which may be derived from either pair of terminals 'when properl \7 connected. This arrangement also avoids a high diiference in potential between the adjacent terminals of the primary and secondary windings of the Tesla. coil.

As a. further protection to the apparatus. the partsare so proportioned and arranged that a short-circuit. either in the spark gap 17 or in the sinusoidal. diagnostic lamp or cautery te1lninals,eannot result. in burning out the transformer. This is due partly to the form 'of the transformer in which the magnetic flux through the core is limited by suitably propm'tioning the end-pieces of the core, and also to the use of sufficient resistance in the secondary coils 3G and 42 and of a sufficiently small number of turns in these coils to prevent the overloading of the primary coils of the transformer.

Thile the various features of my invention are, particularly susceptible to conjoint use inan apparatus of the kind hereinbet'ore referred lto. ,since they all contribute to the production of a safe and reliable apparatus. it will be obvious that the invention in some of its aspects may be embodied in an apparatus from which some of the noted features are omitted.

The invention hereinbefore described is not'limited to .the embodiment specifically illustrated and described, but may be embodied in various 'other forms within the spirit of the inventionand the scope of the following claims.

I claim- 1. An electro--therapelltic apparatus having, in combination, a transformer comprising,l in combination, a transformer provided with a'secondary winding and with a`\primary winding divided 'into two main sections connected in series and normally operative, and' a' plurality of auxiliary sections, a regulating device for controlling the operof the high-tension transformer, and a con- 3' denser interposed in said connection.

4. An electro-.therapeutic apparat-us having, in combination, a high-tension transformer provi-ded with a primary winding and a secondary winding, a high-frequency coil, a condenser, the high-frequency coil andthe condenser being connected in series J with the secondary winding of the hightension transformer, and an independent auxiliary plate 1n said condenser connected with the primary circuit ofgthe high-tensiontransformer and operating as a'safety connection for the high-frequency coil.

5. An electro-therapeutic apparatus having, 1n combination,7 a high-tension transformer provided with a primary winding and a secondary' windingi, a high-frequencycoil connected with and energized by the secondary winding of the transformer, and connections between the high-frequency coil and.

the primary circuitof the transformer constructed and operating as a safety connection between the high-frequency coil and said primary winding.

idw-

6. An electro-therapeutic apparatus ing, in combination, a high-tension transformer provided with a primary winding and a secondary winding, and a condenser and a spark gap vconnected with said secondary winding, the spark 'gap-having 'an adjustable member mounted upon an adjustd ing screw, and a spring-pressed member threaded upon the screw but prevented from rotating therewith, the spring-pressed member operating to preserve electrical contact between the screw and the fixed portion of the spark gap'circuit. l

7. An: electro-therapeutic apparatus having, in combination, a high-tension transi.

former provided with a primary winding anda. secondary winding, and a condenser and a spark gap connected with said sec-` ondary windin the s ark gap comprising a member provi edfwita plurality of heat.- 'f

radiating flanges longitudinally slotted from their periphery inward, and' a xed plate engaging the flanges at their slotted portion and acting as a support for said member.

8. An electro-therapeutic apparatus having, in combination, ahigh-tension transformer provided with a primary winding and a secondary winding, and a condenser.

and aspark gap connected with said .secondar'y winding, the 'spark gap comprising a member provided with a plurality of heatradiating flanges longitudinally slotted`from their periphery inward, ad a fixed-plate engaging the flanges at their slotted por'- tion and acting as a supportfor said member, said plate having a resilient tongu'eengaging the face of one of the flanges to prevent longitudinal movement of the spark gap member upon the plate.

9. An electro-therapeutic apparatus, having, in combination, a -Tesla coil provided with asecondary windin having a portion of greater conductivity Ht an the remainder, and applicator terminals connected across s aid port-ionfor the derivation of currents of greater volume and lower tension than the currents produced inA the secondary winding as a whole'. n

10. An electro-therapeutic apparatus, having, in combination, a high-tension transformer, and a Tesla coil connected with and energize by the transformer and having an electrical connection between its primary and secondary windings, a pair offterminals adapted. to receive applicator conductors connected across the prim-ary winding, and a second pair of terminals adapted to receive applicator conductors connected across the secondary winding, t-he primary and secondary windings being wound in such ldirection that in a circuit formed between one of the primary applicator conductors and one of the secondary applicator conductors and passing through both primary and secondary windings and their connection, the primary and secondary windings will act in opposition to each other.

11. An electro-therapeutic apparatus, having, in combination, `a Tesla coil having a .l

primary` and a secondary winding, terminalsv radapted to receive applicator `conductors connected acrossrthe secondary winding, and a second set` of terminals adapted to receive applicator conductors connected across a4 -portion only of the secondary winding for the derivation of 'currentsof greater Avolume-l and lower tension than the'currents provi duced by the secondary'winding as a whole.

12. An electro-therapeutic apparatus having, in combination, a high-tension trans-- former having. a vprimary wi'ndlng and la secondary winding, a high-frequency coil having a primary winding and a. secondary winding, a condenser connected in series with the secondary winding of thetransformer and the primary winding of the coil, a spark gap connected in shunt with said primary winding condenser, and terminals adapted to receive applicator conductors connected with the terminals of the primary winding of the coil, the connections of the terminals which receive the applicator conductors being entirely independent ofthe other connections with said primary winding so as to prevent the conduction of eX- cessive discharges through the applicator conductors in case of the breakage of any of such connections.

13. An electro-therapeutic apparatus having, in combination, a casing, means located in the casing for producing a high-frequency current of high tension, means located in the casing for producing a low-tension current adapted for energizing a cautery, connections for energizing said means from a common source external to the easing, and eX- ternal terminals mounted on the casing for sa1dh1gh-tension and low-tension currents.

14. An electro-therapeutic apparatus hav-l ing, in combination, transforming devices for producing a high-tension current. and a low-tension current adapted for energizing a translating device, and a common regu,

lator for regulating both of said currents simultaneously.

.15.) An electro-therapeutic apparatus having, in combination, a high-tension transformer provided with a primary winding, and a lplurality of secondary windings, one of said secondary windings being constructed and arranged to produce a high-tension current, a condenser and spark gap connected with said winding to produce an oscillatory discharge, a Tesla coil comprising'a primary and secondary, and having its primary connected in and energized by the high tension secondary winding of the transformer, a set of terminals connected with and energized by another of the transformer secondary windings, this Winding being constructed and arranged to produce a current of comparatively low tension and of same frequency as the primary current, a second set of terminals connected across the primary of the Tesla coil for the derivation of an oscillatory. current of low tension and large volume, a third set of terminals connected across a portion only of the secondary winding of the Tesla coil for the derivation of an oscillatory current of hi her tension and smallerl volumethan that erived from the second 'set of terminals, and a fourth set of terminals connected across the entire secondary winding of the Tesla coil for the derivation of an oscillatory current'of still higher tension and smaller volume.

16. -An electro-therapeutic apparatus having, in combination, a' high tension t-ransformer provided with a primary winding,

ing constructed and arranged to produce a current of comparatively low tension, a second set of terminals connected across the primary win'ding of the Tesla coilA for the derivation of an oscillatory current of comparatively large volume and low tension, and a third set of terminals connected across the secondary winding of the Tesla. coil `for the derivation of an oscillatory current of higher tension and smaller volume.

17.- An electro-therapeutic apparatus having, in combination, a Tesla coil comprising primary and secondary windings, a s et of applicator terminals connected across the primary for the derivation of anoscillatory current of comparatively large volume and low tension, and a second set of applicator terminals connected across the secondary Tesla coil for'the yderivation of an oscillatory current of comparatively small volume and high tension.

18. An electro-therapeutic apparatus having, in combination, a high-tension transformer provided with a primary winding and a plurality of secondary windings, one of said secondary windings being constructed and arranged to produce a high-tension current, a condenser and spark gap con-` nected with said winding to produce an oscillatory discharge, a Tesla coil connected to and energized 4by this high-tension secondary winding of the transformer, a set of applicator terminals connected to the Tesla coil, and a second set of terminals connected with and energized by another of the transformer secondary windings', said windings being constructed and arranged to produce a current of comparativelylow tension, a

common means for regulating simultaneously the currents derived from both sets of terminals, and a second regulating means for regulating the current derived from the first set of terminals independently of the current derived from the second set.

19. An electro-therapeutic apparatus having, in combination, a transformer provided with a primary winding, and a plurality of vsecondary windings, one of said secondary windings having a ratio of turns' to the ,primary windings to produce a current of comparatively low tension, and another of said windings having a ratio of turns tothe highly insulated froni the' first-mentioned primary Winding to producev a, high tension secondary Winding.

current, abondenser and spark gap, together CHARLES E7 CAMPBELL with a Tesla coil, connected with said highte'nsion Winding to produce an oscillatory Witnesses:

discharge, this hightension 'Winding of the HORACE VAN EVEREN,

secondary being Wound separately from and A.' ACKROYD. 

